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Oct. 11, 1966 Filed July 9, 1963 United States Patent 3,277,972 ROCK DRILLING EQUIPMENT Gunnar Lagerstriim, Nacka, Sweden, assignor to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of This invention relates to rock drilling equipment particularly intended for drilling in rock covered by an overburden layer of soil, moraine, filling material or the like. The drilling equipment according to the invention may also be used for drilling into the bottom of Waterways or for drilling holes under water through material covering the bottom and into the underlying rock. The invention may also be used for drilling holes for various types of piles, for telephone or power line poles, road sign poles, and the like.

The rock drill bit used in connection with the invention may be a hammer drill bit, a rotary drill bit, a rolling drill bit, a diamond bit or another type of drill that may be fit for the kind of ground and rock to be drilled In the accompanying drawings some embodiments of the invention are illustrated by way of example.

FIG. 1 is a longitudinal section of a main adapter and a flushing medium supply head as well as of the upper end of a tubular casing and a side view of the upper end of a drill rod means according to the invention.

FIG. 2 is a transverse section on line II-II in FIG 1.

FIG. 3 is a longitudinal section and partial side view of the lower end of a tubular casing and a drill string.

FIG. 4 is a cross section on line lV-IV in FIG. 3.

FIG. 5 is a section similar to FIG. 3 with the drill string in retracted position, and FIG. 6 is a cross section on line VIVI in FIG. 5.

FIG. 7 is a section similar to FIG. 3 of a modification of the casing and drill string according to FIGS. 3-6, and FIG. 8 is a cross section on line VIIIVIII in FIG. 7.

FIG. 9 is a longitudinal section similar to FIG. 7 with the drill string in retracted position, and FIG. 10 is a cross section on line XX in FIG. 9.

FIG. 11 is a side view of the drill bit end of a casing and drill steel according to a further embodiment of the invention, and FIG. 12 is a longitudinal section and partial side view of the upper end of the casing and drill steel according to FIG. 11.

FIG. 13 is a cross section on line XIIIXIII in FIG. 12, and FIG. 14 is a section on line XIV-XIV in FIG. 1 1.

FIG. 15 is a view similar to FIG. 11 in which the drill steel has been retracted into the casing.

The rock drilling equipment illustrated in FIGS. 1l0 consists of a main adapter 1 which in conventional manner, for instance by means of a Leyner shank, is arranged for being actuated by a rock drill (not illustrated) which may be a rotary rock drill or a rock drill with rotary as well as hammering action. The rotary or hammering and rotary energy is transmitted through the main adapter to a drill string or to an integral drill steel. The drill rod may comprise a number of drill rod elements 2 coupled together by means of sleeves 3 and a bit adapter 4.

At the leading end the bit adapter is coupled to a drill bit 5, which according to the working conditions may be a hammer drill bit provided with hard metal inserts,

a roller bit, a diamond bit or any other suitable drill bit. The drill rod and the bit are carried through a tubular casing 6 which may comprise a number of tubular 3,277,972 Patented Oct. 11, 1966 casing elements which may be threaded together directly as illustrated in the drawings or connected by means of coupling sleeves or otherwise as is well known in the art.

The leading casing element 7 is of a special design and in the embodiment of FIGS. 3-6 the leading element 7 forms a bearing surface 8 for a bushing 9 and an annular abutment or shoulder 10 which prevents the bushing 9 from being expelled through the lower end opening of the casing element 7. The bushing 9 has an cecentrically disposed non-circular passage or opening which is partially cylindrical and partially hexagonal and which may, for instance, as illustrated in FIGS. 4 and 6 comprise one half 11 of a circle and one half 12 of a hexagon, as illustrated at 11 and 12. The bit adapter 4 is provided with an eccentric guiding boss 13 which fits the opening 11, 12 so that it can move axially through said opening but is prevented from turning in the bushing 9. The bit adapter has a flushing medium passage 14 which communicates with the flushing medium passage 15 in the drill rod elements 2 and flushing medium passages 16 in the drill bit.

The bushing 9 may have one or more recesses 17 in the peripheral portion forming longitudinal passages through which flushing medium may pass from the passage 18 between the drill rod string 2 and the casing element string 6 in the direction towards the drill bit or in opposite direction. The external diameter of the bushing 9 is so much less than the minimum internal diameter of the casing elements 6, that the bushing 9 may be retracted through the string of casing elements together with the drill rod string and the bit. The bit adapter 4 is furthermore so dimensioned and the guiding boss 13 is so disposed on the bit adapter, that the drill bit and the drill rod string may be moved down through the casing string 6 with the drill bit moving substantially along the axis of the casing and during this motion the bushing 9 is situated substantially around the portion 19 of the bit adapter 4 as illustrated in FIG. 5.

In this relative position of the various parts the drill string including the bushing 9 and bit 5 may be moved down through the casing string until the bushing 9 abuts the shoulder 10 of the leading casing element 7. The drill string is then moved forward a further distance so that the boss 13 enters the opening in the bushing 9 and so that consequently the drill bit arrives outside the end 20 of the casing element 7, as obvious from FIG. 3. Since the boss 13 has entered the opening in the bushing 9 and the bit adapter has been caused to take an eccentric or offset position in casing element 7 the drill bit will now operate in front of and slightly outside the prolongation of the casing element 7, as illustrated in FIG. 3. In this position the drill bit will produce a hole 21 which is slightly larger than the external diameter of the casing element 7. The bushing 9 has a partial upper extension 39 which guides the bit adapter 4 in the bushing in the position illustrated in FIG. 5. The boss 13 has tapering end portions 22, 23 which are helpful when the boss has to enter the bushing 24. The opening 11, 12 in the bushing is so large, that it permits passage of a coupling sleeve 3 in any direction.

At the upper end of the string of casing elements 6 a flushing medium bushing 25 is provided which is screw threaded into the trailing casing element 6 and is provided with a swivel bushing 26 arranged on the outside of the flushing medium bushing for supplying flushing medium through a connection 27 and passages 28 to the passage 18. The main adapter 1 is provided with an annular end surface 29 which abuts the upper end surface 30 of the bushing 25 through which a feeding pressure or feeding force may be transmitted to the string of casing elements so that said string is hammered or pressed down through the ground according to the advance of the drilling. However, rotation cannot be transmitted from the main adapter 1 to the sleeve or bushing 25 and in order to prevent the bushing 25 from rotating due to friction an arresting mechanism is provided which consists of a spring actuated pawl illustrated in section in FIG. 2 and cooperating with teeth 32 on the bushing 25. Percussion energy and pressure may be transmitted from the adapter 1 through a shoulder 33 to the upper end surface 34 of the trailing drill rod element 2 and furthermore through end surfaces 35, 36 to the bit adapter 4 and through end surfaces 37, 38 to the drill bit 5.

When the drilling equipment above described has been used to drill a hole through the overburden down to bed rock the drill string and the bushing 9 may be retracted through the casing string from which the bushing 25 has been removed. Drilling may then continue with a conventional drill string without the adapter 4 and bushing 9 through the casing string to any desired depth in bed rock. Drilling may also be continued without retracting the drill string if a rod element 2 is added at the upper end of the drill string since the boss 13 may follow the drill bit down through the hole and the sleeve 3 may pass through the opening 11, 12 in the bushing 9.

In the modification of the invention illustrated in FIGS. 7l0 the bushing 41 is arranged to remain substantially still without rotating in the casing element 7 during drilling and in this case the bit adapter 4 is provided with an eccentrically disposed or off set guiding boss 42 of circular cross section which is mounted for rotation in the cylindrical opening 40 in the bushing 41, FIG. 8. The other details of the embodiment in FIGS. 7-l0 have been indicated with the same reference numerals as in FIGS. 3-6 and are not described again.

The embodiment of the invention illustrated in FIGS. 11-15 is particularly useful for relatively short holes such as telephone pole holes, holes for road sign posts, or the like. In this embodiment the illustrated equipment comprises a tubular casing 50 which is recessed at one side of the leading end as indicated at 51 so that a side opening is formed at this end of the casing. The casing is illustrated in the present case as a one piece casing but for longer holes the casing may naturally be built up by several casing elements, screwed together or connected in any other suitable way. An integral drill steel such as a hexagon drill steel 52 provided with a cruciform drill bit 53 and a conventional hexagon shank 54 and a collar 55 extends through the casing 50. A split bushing 56, 57 which has a hexagonal opening 58 and external flange portions 59, 60 is inserted in the upper end of the casing 50 around the drill steel, as illustrated in FIGS. 12 and 13. The bushing portion 57 forms a lug 61 which engages a corresponding recess 62 in the upper end of the casing 50 so that the bushing 56, 57 can not rotate in the casing. The underside 63 of the flanges 59, 60 engages the end surface 64 of the casing, whereas the collar 55 is normally pressed against the upper surface 65 of the flange 59, 60 which is preferably rounded to fit the collar 55. At the leading end of the casing 50 a crescent shaped guide body 66 is welded or otherwise secured to the inner side of the wall of the casing 50. Said guide body is so dimensioned that the drill bit, when moved to the bottom of the casing, rides out somewhat outside the casing on the guide body. During drilling the drill steel as well as the casing is rotated by the rock drill and it is obvious that the drill bit will produce a hole 67 which is slightly larger than the external diameter of the casing. The drill steel is slightly bent during drilling as obvious from FIG. 11 but it has been found that the usual clearance in drill chucks and the elasticity of the drill steel is quite sufficient to permit this minor bending. Flushing of the drill hole is in this embodiment carried out in conventional 4- manner, for instance by air flushing through the flushing passage 68 of the drill steel.

The embodiments of the invention above described should only be considered as examples and may be modified in several different Ways within the scope of the claims.

What I claimis:

1. In drilling apparatus of the character described having a tubular casing and drill rod means including a drill bit disposed at one end thereof for movement axially through and beyond said casing, the combination which comprises guiding means disposed in said casing substantially adjacent the end thereof nearest said drill bit for cooperating sliding engagement at one axial position of said drill rod means in said casing for maintaining said drill rod means and said drill bit offset from the axis of said casing, said guiding means forming a constriction within said casing having a smaller open cross section than that of said casing but larger than the greatest transverse cross section of said drill rod means and bit for withdrawing said drill rod means and bit axially through said constriction, and means for suspending said drill rod means and drill bit coaxially within said casing in other relative axial positions thereof when said guiding means are not in engagement.

2. Drilling apparatus as recited in claim 1 in which said guiding means comprises an abutment at at least one side of said casing and cooperating guiding surfaces on said drill rod means for slidably engaging said abutment in said one relative axial position of said drill rod means in said casing.

3. Drilling apparatus according to claim 1, in which said guiding means comprise a boss on said drill rod means adjacent said bit and a bushing inside said casing for receiving said boss in a position to maintain the axis of the drill rod means ofiset to the casing axis so much that said bit extends beyond and just outside the external diameter of said casing.

4. Drilling apparatus according to claim 3, in which said boss has a non-circular outer cross-sectional contour and in which said bushing has a corresponding opening for receiving said boss and preventing rotation of the said boss in the said bushing, the bushing having a cylindrical external bearing surface for close fitting rotational disposition in the axial opening of the said casing.

5. Drilling apparatus according to claim 3, in which the outer periphery of the said boss is circular and in which the bushing has a corresponding opening for rotatably receiving and journalling the said boss therein, the bushing having an external surface providing iclose fitting engagement with the axial opening in said casing.

6. Drilling apparatus according to claim 3, in which the drill rod includes drill rod sections with coupling sleeves connecting adjacent section ends and in which the said bushing has an axial opening for slidingly receiving the said boss and large enough to permit said coupling sleeves to pass axially through said 'bus'hing.

7. Drilling apparatus-as recited in claim 3 which includes a bit adapter forming a part of the drill rod means with said boss carried on said adapter, and in which said boss has a tapering portion at each end thereof for engaging said bushing.

8. Drilling apparatus according to claim 3, in which abutment means are provided inside the said casing to cooperate with the said bushing to maintain the said bushing within the said casing in guiding position adjacent the said drill bit.

9. Drilling apparatus according to claim 8, in which the said abutment means-consists of an annular shoulder at the inner side of the said casingarranged to cooperate with the said bushing to prevent the said bushing from being expelled through the said casing.

10. Drilling apparatus as recited in claim 1 and including means for rotating the said casing, and in which said casing has a side opening at the end adjacent the drill bit and in which the said guide means comprises a body forming bearing means at the opposite inner side of the casing to said side opening arranged to guide the drill bit sideways out through the side opening to produce a hole slightly larger in diameter than the outer diameter of the casing.

11. Drilling apparatus according to claim 10, in which the drill rod has a non-circular collar and portion adjacent the end opposite the bit end, a split bushing fitting around said non-circular portion to prevent relative rotation of said bushing and said portion, said bushing fitting in the casing end opposite the drill bit end with said bushing engaging the said casing in rotation when the said bushing is rotated.

12. Drilling apparatus according to claim 11, in which the split bushing has an external cylindrical portion fitting in the casing, a radial flange extending outside from said cylindrical portion and having an annular surface abutting an annular end surface on the said casing for transmitting axial pressure thereto, a lug cooperating with a recess in the said casing wall for the engagement thereof when said bushing is rotated.

13. Drilling apparatus as recited in claim 1 and including a main adapter attached to the drill rod at an end opposite the drill bit end, said main adapter having coaxial end surfaces with said drill rod and said casing for transmitting percussion energy to said drill rod and to the said casing and a screw threaded portion adjacent the end of said drill rod for transmitting rotation and feeding and retraction force to the said drill rod.

14. Drilling apparatus according to claim 13, in which a flushing medium bushing is attached to the casing end remote from the drill bit with a swivel bushing rotata-bly disposed on the outside thereof for supplying flushing medium to passages in said flushing medium bushing and the interior of the said casing from a source of flushing medium.

References Cited by the Examiner UNITED STATES PATENTS 654,981 7/1900 Howarth et al. 175399 X 2,620,166 12/1952 Waddington 175-398 X CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN BENDETT, Examiner.

W. J. MALONEY, R. E. FAVREAU,

Assistant Examiners. 

1. IN DRILLING APPARATUS OF THE CHARACTER DESCRIBED HAVING A TUBULAR CASING AND DRILL ROD MEANS INCLUDING A DRILL BIT DISPOSED AT ONE END THEREOF FOR MOVEMENT AXIALLY THROUGH AND BEYOND SAID CASING, THE COMBINATION WHICH COMPRISES GUIDING MEANS DISPOSED IN SAID CASING SUBSTANTIALLY ADJACENT THE END THEREOF NEAREST SAID DRILL BIT FOR COOPERATING SLIDING ENGAGEMENT AT ONE AXIAL POSITION OF SAID DRILL ROD MEANS IN SAID CASING FOR MAINTAINING SAID DRILL ROD MEANS AND SAID DRILL BIT OFFSET THE AXIS OF SAID CASING, SAID GUIDING MEANS FORMING A CONSTRICTION WITHIN 